diff --git a/Step.md b/docs/Step01.md
similarity index 100%
rename from Step.md
rename to docs/Step01.md
diff --git a/docs/Step02.md b/docs/Step02.md
new file mode 100644
index 0000000000..f00b4718a8
--- /dev/null
+++ b/docs/Step02.md
@@ -0,0 +1,38 @@
+## 수강 신청 기능 요구사항
+- 과정(Course)은 기수 단위로 운영하며, 여러 개의 강의(Session)를 가질 수 있다. 
+- 강의는 시작일과 종료일을 가진다. 
+- 강의는 강의 커버 이미지 정보를 가진다. 
+  - 이미지 크기는 1MB 이하여야 한다. 
+  - 이미지 타입은 gif, jpg(jpeg 포함),, png, svg만 허용한다. 
+  - 이미지의 width는 300픽셀, height는 200픽셀 이상이어야 하며, width와 height의 비율은 3:2여야 한다.
+- 강의는 무료 강의와 유료 강의로 나뉜다.
+  - 무료 강의는 최대 수강 인원 제한이 없다.
+  - 유료 강의는 강의 최대 수강 인원을 초과할 수 없다.
+  - 유료 강의는 수강생이 결제한 금액과 수강료가 일치할 때 수강 신청이 가능하다.
+- 강의 상태는 준비중, 모집중, 종료 3가지 상태를 가진다.
+- 강의 수강신청은 강의 상태가 모집중일 때만 가능하다.
+- 유료 강의의 경우 결제는 이미 완료한 것으로 가정하고 이후 과정을 구현한다. 
+  - 결제를 완료한 결제 정보는 payments 모듈을 통해 관리되며, 결제 정보는 Payment 객체에 담겨 반한된다.
+
+
+## 클래스 
+- `과정(Course)` : 1
+  - 기수
+
+- `강의(Session)` : N
+  - 금액 : 유료 / 무료
+    - 유료 강의
+      - 강의 최대 `수강 인원` 제한
+      - `결재 금액` = 수강료]
+    - 무료 강의
+      - 최대 수강인원 제한 없음
+  - 상태 : 준비중, 모집중, 종료
+  - 시작일, 종료일 
+  - 강의 커버 이미지 
+
+- `강의 커버 이미지 (SessionCoverImage)`
+  - 크기 : 1MB
+  - 타입 : gif, jpg(jpeg), png, svg
+  - dimension 
+    - width >= 300, height >= 200
+    - width : height = 3 : 2
diff --git a/src/main/java/nextstep/courses/domain/BaseEntity.java b/src/main/java/nextstep/courses/domain/BaseEntity.java
new file mode 100644
index 0000000000..2f8bbf5b31
--- /dev/null
+++ b/src/main/java/nextstep/courses/domain/BaseEntity.java
@@ -0,0 +1,36 @@
+package nextstep.courses.domain;
+
+import java.time.LocalDateTime;
+
+public abstract class BaseEntity {
+    private Long id;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    protected BaseEntity() {
+        this.createdAt = LocalDateTime.now();
+    }
+
+    protected BaseEntity(Long id) {
+        this.id = id;
+        this.createdAt = LocalDateTime.now();
+    }
+
+    protected BaseEntity(Long id, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.id = id;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/nextstep/courses/domain/Course.java b/src/main/java/nextstep/courses/domain/Course.java
deleted file mode 100644
index 0f69716043..0000000000
--- a/src/main/java/nextstep/courses/domain/Course.java
+++ /dev/null
@@ -1,53 +0,0 @@
-package nextstep.courses.domain;
-
-import java.time.LocalDateTime;
-
-public class Course {
-    private Long id;
-
-    private String title;
-
-    private Long creatorId;
-
-    private LocalDateTime createdAt;
-
-    private LocalDateTime updatedAt;
-
-    public Course() {
-    }
-
-    public Course(String title, Long creatorId) {
-        this(0L, title, creatorId, LocalDateTime.now(), null);
-    }
-
-    public Course(Long id, String title, Long creatorId, LocalDateTime createdAt, LocalDateTime updatedAt) {
-        this.id = id;
-        this.title = title;
-        this.creatorId = creatorId;
-        this.createdAt = createdAt;
-        this.updatedAt = updatedAt;
-    }
-
-    public String getTitle() {
-        return title;
-    }
-
-    public Long getCreatorId() {
-        return creatorId;
-    }
-
-    public LocalDateTime getCreatedAt() {
-        return createdAt;
-    }
-
-    @Override
-    public String toString() {
-        return "Course{" +
-                "id=" + id +
-                ", title='" + title + '\'' +
-                ", creatorId=" + creatorId +
-                ", createdAt=" + createdAt +
-                ", updatedAt=" + updatedAt +
-                '}';
-    }
-}
diff --git a/src/main/java/nextstep/courses/domain/course/Course.java b/src/main/java/nextstep/courses/domain/course/Course.java
new file mode 100644
index 0000000000..9e390236f0
--- /dev/null
+++ b/src/main/java/nextstep/courses/domain/course/Course.java
@@ -0,0 +1,61 @@
+package nextstep.courses.domain.course;
+
+import java.time.LocalDateTime;
+import java.util.Objects;
+import nextstep.courses.domain.BaseEntity;
+
+public class Course extends BaseEntity {
+    private String title;
+    private Long creatorId;
+
+    public Course() {
+    }
+
+    public Course(String title, Long creatorId) {
+        this(null, title, creatorId);
+    }
+
+    public Course(Long id, String title, Long creatorId) {
+        super(id);
+        this.title = title;
+        this.creatorId = creatorId;
+    }
+
+    public Course(Long id, String title, Long creatorId, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        super(id, createdAt, updatedAt);
+        this.title = title;
+        this.creatorId = creatorId;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public Long getCreatorId() {
+        return creatorId;
+    }
+
+    @Override
+    public String toString() {
+        return "Course{" +
+                "id=" + getId() +
+                ", title='" + title + '\'' +
+                ", creatorId=" + creatorId +
+                ", createdAt=" + getCreatedAt() +
+                '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        Course course = (Course) o;
+        return Objects.equals(getId(), course.getId());
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hashCode(getId());
+    }
+}
diff --git a/src/main/java/nextstep/courses/domain/CourseRepository.java b/src/main/java/nextstep/courses/domain/course/CourseRepository.java
similarity index 71%
rename from src/main/java/nextstep/courses/domain/CourseRepository.java
rename to src/main/java/nextstep/courses/domain/course/CourseRepository.java
index 6aaeb638d1..28180d25e0 100644
--- a/src/main/java/nextstep/courses/domain/CourseRepository.java
+++ b/src/main/java/nextstep/courses/domain/course/CourseRepository.java
@@ -1,4 +1,4 @@
-package nextstep.courses.domain;
+package nextstep.courses.domain.course;
 
 public interface CourseRepository {
     int save(Course course);
diff --git a/src/main/java/nextstep/courses/domain/image/SessionCoverImage.java b/src/main/java/nextstep/courses/domain/image/SessionCoverImage.java
new file mode 100644
index 0000000000..814e160962
--- /dev/null
+++ b/src/main/java/nextstep/courses/domain/image/SessionCoverImage.java
@@ -0,0 +1,17 @@
+package nextstep.courses.domain.image;
+
+public class SessionCoverImage {
+  private final SessionImageDimension dimension;
+  private final SessionImageExtension extension;
+  private final SessionImageCapacity capacity;
+
+  public SessionCoverImage(int width, int height, String extension, long bytes) {
+    this(new SessionImageDimension(width, height), SessionImageExtension.from(extension), new SessionImageCapacity(bytes));
+  }
+
+  public SessionCoverImage(SessionImageDimension dimension, SessionImageExtension extension, SessionImageCapacity capacity) {
+    this.dimension = dimension;
+    this.extension = extension;
+    this.capacity = capacity;
+  }
+}
diff --git a/src/main/java/nextstep/courses/domain/image/SessionImageCapacity.java b/src/main/java/nextstep/courses/domain/image/SessionImageCapacity.java
new file mode 100644
index 0000000000..d9477c35fc
--- /dev/null
+++ b/src/main/java/nextstep/courses/domain/image/SessionImageCapacity.java
@@ -0,0 +1,29 @@
+package nextstep.courses.domain.image;
+
+public class SessionImageCapacity {
+  private static final long MAX_CAPACITY_BYTES = 1024 * 1024; // 1MB
+  private final long bytes;
+
+  public SessionImageCapacity(long bytes) {
+    validate(bytes);
+    this.bytes = bytes;
+  }
+
+  public static SessionImageCapacity ofKB(long kb) {
+    return new SessionImageCapacity(kb * 1024);
+  }
+
+  public static SessionImageCapacity ofMB(long mb) {
+    return new SessionImageCapacity(mb * 1024 * 1024);
+  }
+
+  private void validate(long bytes) {
+    if (bytes <= 0) {
+      throw new IllegalArgumentException("이미지 크기는 0보다 커야 합니다.");
+    }
+    if (bytes > MAX_CAPACITY_BYTES) {
+      throw new IllegalArgumentException("이미지 크기는 1MB 이하여야 합니다.");
+    }
+  }
+
+}
diff --git a/src/main/java/nextstep/courses/domain/image/SessionImageDimension.java b/src/main/java/nextstep/courses/domain/image/SessionImageDimension.java
new file mode 100644
index 0000000000..f033bb6351
--- /dev/null
+++ b/src/main/java/nextstep/courses/domain/image/SessionImageDimension.java
@@ -0,0 +1,38 @@
+package nextstep.courses.domain.image;
+
+public class SessionImageDimension {
+  private static final int MIN_WIDTH = 300;
+  private static final int MIN_HEIGHT = 200;
+  private static final int RATIO_W = 3;
+  private static final int RATIO_H = 2;
+
+  private int width;
+  private int height;
+
+  public SessionImageDimension(int width, int height) {
+    validateMinLength(width, height);
+    validateRatio(width, height);
+    this.width = width;
+    this.height = height;
+  }
+  private void validateMinLength(int width, int height){
+    if(!(width >= MIN_WIDTH && height >= MIN_HEIGHT)) {
+      throw new IllegalArgumentException("이미지는 가로 300이상, 세로 200 이상이어야 합니다.");
+    }
+  }
+
+  private void validateRatio(int width, int height){
+    int gcd = gcd(width, height);
+    int ratioW = width / gcd;
+    int ratioH = height / gcd;
+    if(!(ratioW == RATIO_W && ratioH == RATIO_H)){
+      throw new IllegalArgumentException("이미지는 가로 x 세로 3대 2이어야 합니다.");
+    }
+  }
+
+  private int gcd(int a, int b) {
+    return b == 0 ? a : gcd(b, a % b);
+  }
+
+
+}
diff --git a/src/main/java/nextstep/courses/domain/image/SessionImageExtension.java b/src/main/java/nextstep/courses/domain/image/SessionImageExtension.java
new file mode 100644
index 0000000000..d1e7515d90
--- /dev/null
+++ b/src/main/java/nextstep/courses/domain/image/SessionImageExtension.java
@@ -0,0 +1,27 @@
+package nextstep.courses.domain.image;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public enum SessionImageExtension {
+  GIF("gif"),
+  JPG("jpg", "jpeg"),
+  PNG("png"),
+  SVG("svg");
+
+  private List<String> names;
+
+  SessionImageExtension(String... names){
+    this.names = new ArrayList<>(List.of(names));
+  }
+
+  public static SessionImageExtension from(String extension) {
+    String lowerExt = extension.toLowerCase();
+    for (SessionImageExtension type : values()) {
+      if (type.names.contains(lowerExt)) {
+        return type;
+      }
+    }
+    throw new IllegalArgumentException("지원하지 않는 이미지 확장자입니다: " + extension);
+  }
+}
diff --git a/src/main/java/nextstep/courses/domain/registration/Registration.java b/src/main/java/nextstep/courses/domain/registration/Registration.java
new file mode 100644
index 0000000000..b9e25cda08
--- /dev/null
+++ b/src/main/java/nextstep/courses/domain/registration/Registration.java
@@ -0,0 +1,23 @@
+package nextstep.courses.domain.registration;
+
+import java.time.LocalDateTime;
+
+public class Registration {
+  private final Long sessionId;
+  private final Long studentId;
+  private final LocalDateTime enrolledAt;
+
+  public Registration(Long sessionId, Long studentId) {
+    this(sessionId, studentId, LocalDateTime.now());
+  }
+
+  public Registration(Long sessionId, Long studentId, LocalDateTime enrolledAt) {
+    this.sessionId = sessionId;
+    this.studentId = studentId;
+    this.enrolledAt = enrolledAt;
+  }
+  public boolean contains(Long studentId) {
+    return this.studentId == studentId;
+  }
+
+}
\ No newline at end of file
diff --git a/src/main/java/nextstep/courses/domain/registration/Registrations.java b/src/main/java/nextstep/courses/domain/registration/Registrations.java
new file mode 100644
index 0000000000..d85102f1ab
--- /dev/null
+++ b/src/main/java/nextstep/courses/domain/registration/Registrations.java
@@ -0,0 +1,33 @@
+package nextstep.courses.domain.registration;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class Registrations {
+  private final List<Registration> registrations;
+
+  public Registrations() {
+    this(new ArrayList<>());
+  }
+
+  public Registrations(List<Registration> registrations) {
+    this.registrations = registrations;
+  }
+
+  public Registrations add(Registration registration) {
+    List<Registration> newList = new ArrayList<>(registrations);
+    newList.add(registration);
+    return new Registrations(newList);
+  }
+
+  public int count() {
+    return registrations.size();
+  }
+
+  public boolean contains(Long studentId) {
+    return registrations.stream()
+        .anyMatch(r -> r.contains(studentId));
+  }
+
+}
\ No newline at end of file
diff --git a/src/main/java/nextstep/courses/domain/session/Enrollment.java b/src/main/java/nextstep/courses/domain/session/Enrollment.java
new file mode 100644
index 0000000000..8349d21eea
--- /dev/null
+++ b/src/main/java/nextstep/courses/domain/session/Enrollment.java
@@ -0,0 +1,41 @@
+package nextstep.courses.domain.session;
+
+import nextstep.courses.domain.session.type.FreeType;
+import nextstep.courses.domain.session.type.SessionType;
+
+public class Enrollment {
+    private SessionState state;
+    private SessionType type;
+
+    public Enrollment() {
+        this(SessionState.PREPARING, new FreeType());
+    }
+
+    public Enrollment(SessionType type) {
+        this(SessionState.PREPARING, type);
+    }
+
+    public Enrollment(SessionState state, SessionType type) {
+        this.state = state;
+        this.type = type;
+    }
+
+    public void enroll(long payAmount) {
+        validateState();
+        this.type = type.enroll(payAmount);
+    }
+
+    public void open() {
+        this.state = state.open();
+    }
+
+    public void close() {
+        this.state = state.close();
+    }
+
+    private void validateState() {
+        if (!state.canEnroll()) {
+            throw new IllegalStateException("모집중인 강의만 수강신청이 가능합니다.");
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/nextstep/courses/domain/session/Session.java b/src/main/java/nextstep/courses/domain/session/Session.java
new file mode 100644
index 0000000000..a506fbbe29
--- /dev/null
+++ b/src/main/java/nextstep/courses/domain/session/Session.java
@@ -0,0 +1,38 @@
+package nextstep.courses.domain.session;
+
+import nextstep.courses.domain.BaseEntity;
+import nextstep.courses.domain.course.Course;
+import nextstep.courses.domain.image.SessionCoverImage;
+
+public class Session extends BaseEntity {
+  private final Course course;
+  private final Term term;
+  private final SessionCoverImage cover;
+  private final SessionPeriod period;
+  private final Enrollment enrollment;
+
+  public Session(Course course, int term, SessionCoverImage cover, String startDay, String endDay) {
+    this(null, course, new Term(term), cover, new SessionPeriod(startDay, endDay), new Enrollment());
+  }
+
+  public Session(Long id, Course course, Term term, SessionCoverImage cover, SessionPeriod period, Enrollment enrollment) {
+    super(id);
+    this.course = course;
+    this.term = term;
+    this.cover = cover;
+    this.period = period;
+    this.enrollment = enrollment;
+  }
+
+  public void enroll(long payAmount) {
+    enrollment.enroll(payAmount);
+  }
+
+  public void open() {
+    enrollment.open();
+  }
+
+  public void close() {
+    enrollment.close();
+  }
+}
diff --git a/src/main/java/nextstep/courses/domain/session/SessionPeriod.java b/src/main/java/nextstep/courses/domain/session/SessionPeriod.java
new file mode 100644
index 0000000000..af5089b4c3
--- /dev/null
+++ b/src/main/java/nextstep/courses/domain/session/SessionPeriod.java
@@ -0,0 +1,24 @@
+package nextstep.courses.domain.session;
+
+import java.time.LocalDate;
+
+public class SessionPeriod {
+  private final LocalDate startDay;
+  private final LocalDate endDay;
+
+  public SessionPeriod(String startDay, String endDay) {
+    this(LocalDate.parse(startDay), LocalDate.parse(endDay));
+  }
+
+  public SessionPeriod(LocalDate startDay, LocalDate endDay) {
+    validate(startDay, endDay);
+    this.startDay = startDay;
+    this.endDay = endDay;
+  }
+
+  private void validate(LocalDate startDay, LocalDate endDay) {
+    if (startDay.isAfter(endDay)) {
+      throw new IllegalArgumentException("시작일은 종료일보다 이전이어야 합니다.");
+    }
+  }
+}
diff --git a/src/main/java/nextstep/courses/domain/session/SessionState.java b/src/main/java/nextstep/courses/domain/session/SessionState.java
new file mode 100644
index 0000000000..a0cab17411
--- /dev/null
+++ b/src/main/java/nextstep/courses/domain/session/SessionState.java
@@ -0,0 +1,25 @@
+package nextstep.courses.domain.session;
+
+public enum SessionState {
+  PREPARING,
+  RECRUITING,
+  CLOSED;
+
+  public SessionState open() {
+    if (this != PREPARING) {
+      throw new IllegalStateException("준비중인 강의만 모집을 시작할 수 있습니다.");
+    }
+    return RECRUITING;
+  }
+
+  public SessionState close() {
+    if (this != RECRUITING) {
+      throw new IllegalStateException("모집중인 강의만 종료할 수 있습니다.");
+    }
+    return CLOSED;
+  }
+
+  public boolean canEnroll() {
+    return this == RECRUITING;
+  }
+}
\ No newline at end of file
diff --git a/src/main/java/nextstep/courses/domain/session/Term.java b/src/main/java/nextstep/courses/domain/session/Term.java
new file mode 100644
index 0000000000..66523f35d7
--- /dev/null
+++ b/src/main/java/nextstep/courses/domain/session/Term.java
@@ -0,0 +1,37 @@
+package nextstep.courses.domain.session;
+
+import java.util.Objects;
+
+public class Term {
+  private static final int MIN_TERM = 1;
+
+  private final int value;
+
+  public Term(int value) {
+    validate(value);
+    this.value = value;
+  }
+
+  private void validate(int value) {
+    if (value < MIN_TERM) {
+      throw new IllegalArgumentException("기수는 " + MIN_TERM + " 이상이어야 합니다.");
+    }
+  }
+
+  public int getValue() {
+    return value;
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) return true;
+    if (o == null || getClass() != o.getClass()) return false;
+    Term term = (Term) o;
+    return value == term.value;
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(value);
+  }
+}
\ No newline at end of file
diff --git a/src/main/java/nextstep/courses/domain/session/type/FreeType.java b/src/main/java/nextstep/courses/domain/session/type/FreeType.java
new file mode 100644
index 0000000000..b6b425d1af
--- /dev/null
+++ b/src/main/java/nextstep/courses/domain/session/type/FreeType.java
@@ -0,0 +1,9 @@
+package nextstep.courses.domain.session.type;
+
+public class FreeType implements SessionType {
+
+    @Override
+    public SessionType enroll(long payAmount) {
+        return this;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/nextstep/courses/domain/session/type/PaidType.java b/src/main/java/nextstep/courses/domain/session/type/PaidType.java
new file mode 100644
index 0000000000..dc680bca29
--- /dev/null
+++ b/src/main/java/nextstep/courses/domain/session/type/PaidType.java
@@ -0,0 +1,55 @@
+package nextstep.courses.domain.session.type;
+
+import java.util.Objects;
+
+public class PaidType implements SessionType {
+    private final int maxCapacity;
+    private final long tuitionFee;
+    private final int studentCount;
+
+    public PaidType(int maxCapacity, long tuitionFee) {
+        this(maxCapacity, tuitionFee, 0);
+    }
+
+    public PaidType(int maxCapacity, long tuitionFee, int studentCount) {
+        validateCapacity(maxCapacity, studentCount);
+        this.maxCapacity = maxCapacity;
+        this.tuitionFee = tuitionFee;
+        this.studentCount = studentCount;
+    }
+
+    @Override
+    public SessionType enroll(long payAmount) {
+        int newCount = studentCount + 1;
+        validateCapacity(maxCapacity, newCount);
+        validateTuitionFee(payAmount);
+        return new PaidType(maxCapacity, tuitionFee, newCount);
+    }
+
+    private void validateCapacity(int maxCapacity, int studentCount) {
+        if (maxCapacity < studentCount) {
+            throw new IllegalArgumentException("최대 수강 인원을 초과할 수 없습니다.");
+        }
+    }
+
+    private void validateTuitionFee(long payAmount) {
+        if (payAmount != tuitionFee) {
+            throw new IllegalArgumentException("수강료와 지불한 금액이 정확히 일치해야 합니다.");
+        }
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        PaidType that = (PaidType) o;
+        return maxCapacity == that.maxCapacity
+            && tuitionFee == that.tuitionFee
+            && studentCount == that.studentCount;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(maxCapacity, tuitionFee, studentCount);
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/nextstep/courses/domain/session/type/SessionType.java b/src/main/java/nextstep/courses/domain/session/type/SessionType.java
new file mode 100644
index 0000000000..3998c88427
--- /dev/null
+++ b/src/main/java/nextstep/courses/domain/session/type/SessionType.java
@@ -0,0 +1,5 @@
+package nextstep.courses.domain.session.type;
+
+public interface SessionType {
+    SessionType enroll(long payAmount);
+}
\ No newline at end of file
diff --git a/src/main/java/nextstep/courses/infrastructure/JdbcCourseRepository.java b/src/main/java/nextstep/courses/infrastructure/JdbcCourseRepository.java
index f9122cbe33..7489afc31d 100644
--- a/src/main/java/nextstep/courses/infrastructure/JdbcCourseRepository.java
+++ b/src/main/java/nextstep/courses/infrastructure/JdbcCourseRepository.java
@@ -1,7 +1,7 @@
 package nextstep.courses.infrastructure;
 
-import nextstep.courses.domain.Course;
-import nextstep.courses.domain.CourseRepository;
+import nextstep.courses.domain.course.Course;
+import nextstep.courses.domain.course.CourseRepository;
 import org.springframework.jdbc.core.JdbcOperations;
 import org.springframework.jdbc.core.RowMapper;
 import org.springframework.stereotype.Repository;
diff --git a/src/main/java/nextstep/courses/service/SessionEnrollService.java b/src/main/java/nextstep/courses/service/SessionEnrollService.java
new file mode 100644
index 0000000000..5b12a385a7
--- /dev/null
+++ b/src/main/java/nextstep/courses/service/SessionEnrollService.java
@@ -0,0 +1,16 @@
+package nextstep.courses.service;
+
+import nextstep.courses.domain.course.CourseRepository;
+import nextstep.courses.domain.session.Session;
+import nextstep.payments.domain.Payment;
+import org.springframework.stereotype.Service;
+
+@Service
+public class SessionEnrollService {
+  private CourseRepository courseRepository;
+
+  public void enroll(Session session, Payment payment){
+    session.enroll(payment.getAmount());
+  }
+
+}
diff --git a/src/main/java/nextstep/payments/domain/Payment.java b/src/main/java/nextstep/payments/domain/Payment.java
index 57d833f851..8dcd2fa39a 100644
--- a/src/main/java/nextstep/payments/domain/Payment.java
+++ b/src/main/java/nextstep/payments/domain/Payment.java
@@ -26,4 +26,16 @@ public Payment(String id, Long sessionId, Long nsUserId, Long amount) {
         this.amount = amount;
         this.createdAt = LocalDateTime.now();
     }
+
+    public Long getSessionId() {
+        return sessionId;
+    }
+
+    public Long getNsUserId() {
+        return nsUserId;
+    }
+
+    public Long getAmount() {
+        return amount;
+    }
 }
diff --git a/src/test/java/nextstep/courses/domain/course/CourseTest.java b/src/test/java/nextstep/courses/domain/course/CourseTest.java
new file mode 100644
index 0000000000..19f32d5394
--- /dev/null
+++ b/src/test/java/nextstep/courses/domain/course/CourseTest.java
@@ -0,0 +1,5 @@
+package nextstep.courses.domain.course;
+
+class CourseTest {
+
+}
\ No newline at end of file
diff --git a/src/test/java/nextstep/courses/domain/image/SessionCoverImageTest.java b/src/test/java/nextstep/courses/domain/image/SessionCoverImageTest.java
new file mode 100644
index 0000000000..795afcfeee
--- /dev/null
+++ b/src/test/java/nextstep/courses/domain/image/SessionCoverImageTest.java
@@ -0,0 +1,28 @@
+package nextstep.courses.domain.image;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+class SessionCoverImageTest {
+  private static final int WIDTH = 300, HEIGHT = 200;
+  private static final long VALID_BYTES = 1024 * 500; // 500KB
+
+  @ParameterizedTest
+  @CsvSource({"gif","jpg","jpeg", "png", "svg"})
+  void 허용된_확장자(String extension){
+    assertDoesNotThrow(() -> new SessionCoverImage(WIDTH, HEIGHT, extension, VALID_BYTES));
+  }
+
+  @ParameterizedTest
+  @CsvSource({"webp"})
+  void 허용하지않은_확장자는_예외(String extension){
+    assertThatThrownBy(() -> new SessionCoverImage(WIDTH, HEIGHT, extension, VALID_BYTES))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("지원하지 않는 이미지 확장자입니다: " + extension);
+  }
+
+
+}
\ No newline at end of file
diff --git a/src/test/java/nextstep/courses/domain/image/SessionImageCapacityTest.java b/src/test/java/nextstep/courses/domain/image/SessionImageCapacityTest.java
new file mode 100644
index 0000000000..b5be7d09c8
--- /dev/null
+++ b/src/test/java/nextstep/courses/domain/image/SessionImageCapacityTest.java
@@ -0,0 +1,48 @@
+package nextstep.courses.domain.image;
+
+import static org.assertj.core.api.Assertions.assertThatCode;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import org.junit.jupiter.api.Test;
+
+class SessionImageCapacityTest {
+
+  @Test
+  void 크기_1MB이하_정상생성() {
+    assertThatCode(() -> new SessionImageCapacity(1024 * 1024))
+        .doesNotThrowAnyException();
+  }
+
+  @Test
+  void 크기_1MB초과_예외() {
+    assertThatThrownBy(() -> new SessionImageCapacity(1024 * 1024 + 1))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("이미지 크기는 1MB 이하여야 합니다.");
+  }
+
+  @Test
+  void 크기_0이하_예외() {
+    assertThatThrownBy(() -> new SessionImageCapacity(0))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("이미지 크기는 0보다 커야 합니다.");
+  }
+
+  @Test
+  void KB단위_생성() {
+    assertThatCode(() -> SessionImageCapacity.ofKB(500))
+        .doesNotThrowAnyException();
+  }
+
+  @Test
+  void MB단위_1MB_정상생성() {
+    assertThatCode(() -> SessionImageCapacity.ofMB(1))
+        .doesNotThrowAnyException();
+  }
+
+  @Test
+  void MB단위_2MB_예외() {
+    assertThatThrownBy(() -> SessionImageCapacity.ofMB(2))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("이미지 크기는 1MB 이하여야 합니다.");
+  }
+}
\ No newline at end of file
diff --git a/src/test/java/nextstep/courses/domain/image/SessionImageDimensionTest.java b/src/test/java/nextstep/courses/domain/image/SessionImageDimensionTest.java
new file mode 100644
index 0000000000..82328a6598
--- /dev/null
+++ b/src/test/java/nextstep/courses/domain/image/SessionImageDimensionTest.java
@@ -0,0 +1,40 @@
+package nextstep.courses.domain.image;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+class SessionImageDimensionTest {
+
+  @ParameterizedTest
+  @CsvSource({"300,200"})
+  void 너비는_300이상_높이는_200이상(int width, int height){
+    assertDoesNotThrow(() -> new SessionImageDimension(width, height));
+  }
+
+  @ParameterizedTest
+  @CsvSource({"299,299", "299,300", "300,199"})
+  void 그_외_너비_예외(int width, int height){
+    assertThatThrownBy(() -> new SessionImageDimension(width, height))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("이미지는 가로 300이상, 세로 200 이상이어야 합니다.");
+  }
+
+  @ParameterizedTest
+  @CsvSource({"300,200","1200,800"})
+  void 너비와_높이_비율은_3_대_2(int width, int height){
+    assertDoesNotThrow(() -> new SessionImageDimension(width, height));
+
+  }
+
+  @ParameterizedTest
+  @CsvSource({"400,200", "600,300", "900,400"})
+  void 그_외_비율_예외(int width, int height){
+    assertThatThrownBy(() -> new SessionImageDimension(width, height))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("이미지는 가로 x 세로 3대 2이어야 합니다.");
+  }
+
+}
\ No newline at end of file
diff --git a/src/test/java/nextstep/courses/domain/session/SessionBuilder.java b/src/test/java/nextstep/courses/domain/session/SessionBuilder.java
new file mode 100644
index 0000000000..76061345e8
--- /dev/null
+++ b/src/test/java/nextstep/courses/domain/session/SessionBuilder.java
@@ -0,0 +1,65 @@
+package nextstep.courses.domain.session;
+
+import nextstep.courses.domain.course.Course;
+import nextstep.courses.domain.image.SessionCoverImage;
+import nextstep.courses.domain.session.type.FreeType;
+import nextstep.courses.domain.session.type.SessionType;
+
+public class SessionBuilder {
+    private Long id = null;
+    private Course course = new Course("TDD", 1L);
+    private Term term = new Term(1);
+    private SessionCoverImage cover = new SessionCoverImage(300, 200, "png", 1024 * 500);
+    private SessionPeriod period = new SessionPeriod("2025-01-01", "2025-01-31");
+    private SessionState state = SessionState.PREPARING;
+    private SessionType type = new FreeType();
+
+    public static SessionBuilder aSession() {
+        return new SessionBuilder();
+    }
+
+    public SessionBuilder withId(Long id) {
+        this.id = id;
+        return this;
+    }
+
+    public SessionBuilder withCourse(Course course) {
+        this.course = course;
+        return this;
+    }
+
+    public SessionBuilder withTerm(int term) {
+        this.term = new Term(term);
+        return this;
+    }
+
+    public SessionBuilder withCover(SessionCoverImage cover) {
+        this.cover = cover;
+        return this;
+    }
+
+    public SessionBuilder withPeriod(String startDay, String endDay) {
+        this.period = new SessionPeriod(startDay, endDay);
+        return this;
+    }
+
+    public SessionBuilder withState(SessionState state) {
+        this.state = state;
+        return this;
+    }
+
+    public SessionBuilder withType(SessionType type) {
+        this.type = type;
+        return this;
+    }
+
+    public SessionBuilder recruiting() {
+        this.state = SessionState.RECRUITING;
+        return this;
+    }
+
+    public Session build() {
+        Enrollment enrollment = new Enrollment(state, type);
+        return new Session(id, course, term, cover, period, enrollment);
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/nextstep/courses/domain/session/SessionPeriodTest.java b/src/test/java/nextstep/courses/domain/session/SessionPeriodTest.java
new file mode 100644
index 0000000000..9e27524fbc
--- /dev/null
+++ b/src/test/java/nextstep/courses/domain/session/SessionPeriodTest.java
@@ -0,0 +1,38 @@
+package nextstep.courses.domain.session;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.assertj.core.api.Assertions.assertThatCode;
+
+import java.time.LocalDate;
+import org.junit.jupiter.api.Test;
+
+class SessionPeriodTest {
+
+  @Test
+  void 시작일이_종료일보다_이전이면_정상_생성() {
+    assertThatCode(() -> new SessionPeriod("2024-01-01", "2024-01-31"))
+        .doesNotThrowAnyException();
+  }
+
+  @Test
+  void 시작일과_종료일이_같으면_정상_생성() {
+    assertThatCode(() -> new SessionPeriod("2024-01-01", "2024-01-01"))
+        .doesNotThrowAnyException();
+  }
+
+  @Test
+  void 시작일이_종료일보다_이후면_예외() {
+    assertThatThrownBy(() -> new SessionPeriod("2024-01-31", "2024-01-01"))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("시작일은 종료일보다 이전이어야 합니다.");
+  }
+
+  @Test
+  void LocalDate로_생성() {
+    LocalDate start = LocalDate.of(2024, 1, 1);
+    LocalDate end = LocalDate.of(2024, 1, 31);
+
+    assertThatCode(() -> new SessionPeriod(start, end))
+        .doesNotThrowAnyException();
+  }
+}
\ No newline at end of file
diff --git a/src/test/java/nextstep/courses/domain/session/SessionStateTest.java b/src/test/java/nextstep/courses/domain/session/SessionStateTest.java
new file mode 100644
index 0000000000..bbd4439a3a
--- /dev/null
+++ b/src/test/java/nextstep/courses/domain/session/SessionStateTest.java
@@ -0,0 +1,48 @@
+package nextstep.courses.domain.session;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import org.junit.jupiter.api.Test;
+
+class SessionStateTest {
+
+  @Test
+  void 준비중에서_모집시작_가능() {
+    assertThat(SessionState.PREPARING.open()).isEqualTo(SessionState.RECRUITING);
+  }
+
+  @Test
+  void 모집중에서_종료_가능() {
+    assertThat(SessionState.RECRUITING.close()).isEqualTo(SessionState.CLOSED);
+  }
+
+  @Test
+  void 준비중이_아닐때_모집시작하면_예외() {
+    assertThatThrownBy(() -> SessionState.RECRUITING.open())
+        .isInstanceOf(IllegalStateException.class)
+        .hasMessage("준비중인 강의만 모집을 시작할 수 있습니다.");
+
+    assertThatThrownBy(() -> SessionState.CLOSED.open())
+        .isInstanceOf(IllegalStateException.class)
+        .hasMessage("준비중인 강의만 모집을 시작할 수 있습니다.");
+  }
+
+  @Test
+  void 모집중이_아닐때_종료하면_예외() {
+    assertThatThrownBy(() -> SessionState.PREPARING.close())
+        .isInstanceOf(IllegalStateException.class)
+        .hasMessage("모집중인 강의만 종료할 수 있습니다.");
+
+    assertThatThrownBy(() -> SessionState.CLOSED.close())
+        .isInstanceOf(IllegalStateException.class)
+        .hasMessage("모집중인 강의만 종료할 수 있습니다.");
+  }
+
+  @Test
+  void 모집중일때만_수강신청_가능() {
+    assertThat(SessionState.PREPARING.canEnroll()).isFalse();
+    assertThat(SessionState.RECRUITING.canEnroll()).isTrue();
+    assertThat(SessionState.CLOSED.canEnroll()).isFalse();
+  }
+}
\ No newline at end of file
diff --git a/src/test/java/nextstep/courses/domain/session/SessionTest.java b/src/test/java/nextstep/courses/domain/session/SessionTest.java
new file mode 100644
index 0000000000..21513ea3c1
--- /dev/null
+++ b/src/test/java/nextstep/courses/domain/session/SessionTest.java
@@ -0,0 +1,44 @@
+package nextstep.courses.domain.session;
+
+import static nextstep.courses.domain.session.SessionBuilder.aSession;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+
+import org.junit.jupiter.api.Test;
+
+class SessionTest {
+
+  @Test
+  void 모집중일때_수강신청_가능() {
+    Session session = aSession().recruiting().build();
+
+    assertDoesNotThrow(() -> session.enroll(0));
+  }
+
+  @Test
+  void 모집중이_아닐때_수강신청하면_예외() {
+    Session session = aSession().build();
+
+    assertThatThrownBy(() -> session.enroll(0))
+        .isInstanceOf(IllegalStateException.class)
+        .hasMessage("모집중인 강의만 수강신청이 가능합니다.");
+  }
+
+  @Test
+  void 준비중이_아닐때_모집시작하면_예외() {
+    Session session = aSession().recruiting().build();
+
+    assertThatThrownBy(() -> session.open())
+        .isInstanceOf(IllegalStateException.class)
+        .hasMessage("준비중인 강의만 모집을 시작할 수 있습니다.");
+  }
+
+  @Test
+  void 모집중이_아닐때_종료하면_예외() {
+    Session session = aSession().build();
+
+    assertThatThrownBy(() -> session.close())
+        .isInstanceOf(IllegalStateException.class)
+        .hasMessage("모집중인 강의만 종료할 수 있습니다.");
+  }
+}
\ No newline at end of file
diff --git a/src/test/java/nextstep/courses/domain/session/type/FreeTypeTest.java b/src/test/java/nextstep/courses/domain/session/type/FreeTypeTest.java
new file mode 100644
index 0000000000..bc01653de8
--- /dev/null
+++ b/src/test/java/nextstep/courses/domain/session/type/FreeTypeTest.java
@@ -0,0 +1,34 @@
+package nextstep.courses.domain.session.type;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatCode;
+
+import nextstep.courses.domain.session.type.FreeType;
+import nextstep.courses.domain.session.type.SessionType;
+import org.junit.jupiter.api.Test;
+
+class FreeTypeTest {
+
+  @Test
+  void 수강인원_제한없음() {
+    SessionType type = new FreeType();
+
+    for (int i = 0; i < 1000; i++) {
+      type = type.enroll(0);
+    }
+
+    assertThat(type).isInstanceOf(FreeType.class);
+  }
+
+  @Test
+  void 금액_상관없이_수강가능() {
+    SessionType type = new FreeType();
+
+    assertThatCode(() -> type.enroll(0))
+        .doesNotThrowAnyException();
+    assertThatCode(() -> type.enroll(100))
+        .doesNotThrowAnyException();
+    assertThatCode(() -> type.enroll(999999))
+        .doesNotThrowAnyException();
+  }
+}
\ No newline at end of file
diff --git a/src/test/java/nextstep/courses/domain/session/type/PaidTypeTest.java b/src/test/java/nextstep/courses/domain/session/type/PaidTypeTest.java
new file mode 100644
index 0000000000..da71011700
--- /dev/null
+++ b/src/test/java/nextstep/courses/domain/session/type/PaidTypeTest.java
@@ -0,0 +1,36 @@
+package nextstep.courses.domain.session.type;
+
+import static org.assertj.core.api.Assertions.assertThatCode;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import nextstep.courses.domain.session.type.PaidType;
+import org.junit.jupiter.api.Test;
+
+class PaidTypeTest {
+
+  @Test
+  void 최대수강인원_초과하면_예외() {
+    PaidType type = new PaidType(300, 1000, 300);
+
+    assertThatThrownBy(() -> type.enroll(1000))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("최대 수강 인원을 초과할 수 없습니다.");
+  }
+
+  @Test
+  void 결제금액과_수강료가_동일하지_않으면_예외() {
+    PaidType type = new PaidType(300, 1000);
+
+    assertThatThrownBy(() -> type.enroll(999))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("수강료와 지불한 금액이 정확히 일치해야 합니다.");
+  }
+
+  @Test
+  void 최대수강인원이하_결제금액과수강료동일하면_성공() {
+    PaidType type = new PaidType(300, 1000);
+
+    assertThatCode(() -> type.enroll(1000))
+        .doesNotThrowAnyException();
+  }
+}
\ No newline at end of file
diff --git a/src/test/java/nextstep/courses/infrastructure/CourseRepositoryTest.java b/src/test/java/nextstep/courses/infrastructure/CourseRepositoryTest.java
index f087fc0ad2..530375d3e1 100644
--- a/src/test/java/nextstep/courses/infrastructure/CourseRepositoryTest.java
+++ b/src/test/java/nextstep/courses/infrastructure/CourseRepositoryTest.java
@@ -1,7 +1,7 @@
 package nextstep.courses.infrastructure;
 
-import nextstep.courses.domain.Course;
-import nextstep.courses.domain.CourseRepository;
+import nextstep.courses.domain.course.Course;
+import nextstep.courses.domain.course.CourseRepository;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.slf4j.Logger;